Detection of a Hypercharge Axion in ATLAS
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Particle Physics Dr Victoria Martin, Spring Semester 2012 Lecture 12: Hadron Decays
Particle Physics Dr Victoria Martin, Spring Semester 2012 Lecture 12: Hadron Decays !Resonances !Heavy Meson and Baryons !Decays and Quantum numbers !CKM matrix 1 Announcements •No lecture on Friday. •Remaining lectures: •Tuesday 13 March •Friday 16 March •Tuesday 20 March •Friday 23 March •Tuesday 27 March •Friday 30 March •Tuesday 3 April •Remaining Tutorials: •Monday 26 March •Monday 2 April 2 From Friday: Mesons and Baryons Summary • Quarks are confined to colourless bound states, collectively known as hadrons: " mesons: quark and anti-quark. Bosons (s=0, 1) with a symmetric colour wavefunction. " baryons: three quarks. Fermions (s=1/2, 3/2) with antisymmetric colour wavefunction. " anti-baryons: three anti-quarks. • Lightest mesons & baryons described by isospin (I, I3), strangeness (S) and hypercharge Y " isospin I=! for u and d quarks; (isospin combined as for spin) " I3=+! (isospin up) for up quarks; I3="! (isospin down) for down quarks " S=+1 for strange quarks (additive quantum number) " hypercharge Y = S + B • Hadrons display SU(3) flavour symmetry between u d and s quarks. Used to predict the allowed meson and baryon states. • As baryons are fermions, the overall wavefunction must be anti-symmetric. The wavefunction is product of colour, flavour, spin and spatial parts: ! = "c "f "S "L an odd number of these must be anti-symmetric. • consequences: no uuu, ddd or sss baryons with total spin J=# (S=#, L=0) • Residual strong force interactions between colourless hadrons propagated by mesons. 3 Resonances • Hadrons which decay due to the strong force have very short lifetime # ~ 10"24 s • Evidence for the existence of these states are resonances in the experimental data Γ2/4 σ = σ • Shape is Breit-Wigner distribution: max (E M)2 + Γ2/4 14 41. -
Electro-Weak Interactions
Electro-weak interactions Marcello Fanti Physics Dept. | University of Milan M. Fanti (Physics Dep., UniMi) Fundamental Interactions 1 / 36 The ElectroWeak model M. Fanti (Physics Dep., UniMi) Fundamental Interactions 2 / 36 Electromagnetic vs weak interaction Electromagnetic interactions mediated by a photon, treat left/right fermions in the same way g M = [¯u (eγµ)u ] − µν [¯u (eγν)u ] 3 1 q2 4 2 1 − γ5 Weak charged interactions only apply to left-handed component: = L 2 Fermi theory (effective low-energy theory): GF µ 5 ν 5 M = p u¯3γ (1 − γ )u1 gµν u¯4γ (1 − γ )u2 2 Complete theory with a vector boson W mediator: g 1 − γ5 g g 1 − γ5 p µ µν p ν M = u¯3 γ u1 − 2 2 u¯4 γ u2 2 2 q − MW 2 2 2 g µ 5 ν 5 −−−! u¯3γ (1 − γ )u1 gµν u¯4γ (1 − γ )u2 2 2 low q 8 MW p 2 2 g −5 −2 ) GF = | and from weak decays GF = (1:1663787 ± 0:0000006) · 10 GeV 8 MW M. Fanti (Physics Dep., UniMi) Fundamental Interactions 3 / 36 Experimental facts e e Electromagnetic interactions γ Conserves charge along fermion lines ¡ Perfectly left/right symmetric e e Long-range interaction electromagnetic µ ) neutral mass-less mediator field A (the photon, γ) currents eL νL Weak charged current interactions Produces charge variation in the fermions, ∆Q = ±1 W ± Acts only on left-handed component, !! ¡ L u Short-range interaction L dL ) charged massive mediator field (W ±)µ weak charged − − − currents E.g. -
Introduction to Flavour Physics
Introduction to flavour physics Y. Grossman Cornell University, Ithaca, NY 14853, USA Abstract In this set of lectures we cover the very basics of flavour physics. The lec- tures are aimed to be an entry point to the subject of flavour physics. A lot of problems are provided in the hope of making the manuscript a self-study guide. 1 Welcome statement My plan for these lectures is to introduce you to the very basics of flavour physics. After the lectures I hope you will have enough knowledge and, more importantly, enough curiosity, and you will go on and learn more about the subject. These are lecture notes and are not meant to be a review. In the lectures, I try to talk about the basic ideas, hoping to give a clear picture of the physics. Thus many details are omitted, implicit assumptions are made, and no references are given. Yet details are important: after you go over the current lecture notes once or twice, I hope you will feel the need for more. Then it will be the time to turn to the many reviews [1–10] and books [11, 12] on the subject. I try to include many homework problems for the reader to solve, much more than what I gave in the actual lectures. If you would like to learn the material, I think that the problems provided are the way to start. They force you to fully understand the issues and apply your knowledge to new situations. The problems are given at the end of each section. -
Kaon to Two Pions Decays from Lattice QCD: ∆I = 1/2 Rule and CP
Kaon to Two Pions decays from Lattice QCD: ∆I =1/2 rule and CP violation Qi Liu Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Graduate School of Arts and Sciences COLUMBIA UNIVERSITY 2012 c 2012 Qi Liu All Rights Reserved Abstract Kaon to Two Pions decays from Lattice QCD: ∆I =1/2 rule and CP violation Qi Liu We report a direct lattice calculation of the K to ππ decay matrix elements for both the ∆I = 1/2 and 3/2 amplitudes A0 and A2 on a 2+1 flavor, domain wall fermion, 163 32 16 lattice ensemble and a 243 64 16 lattice ensemble. This × × × × is a complete calculation in which all contractions for the required ten, four-quark operators are evaluated, including the disconnected graphs in which no quark line connects the initial kaon and final two-pion states. These lattice operators are non- perturbatively renormalized using the Rome-Southampton method and the quadratic divergences are studied and removed. This is an important but notoriously difficult calculation, requiring high statistics on a large volume. In this work we take a major step towards the computation of the physical K ππ amplitudes by performing → a complete calculation at unphysical kinematics with pions of mass 422MeV and 329MeV at rest in the kaon rest frame. With this simplification we are able to 3 resolve Re(A0) from zero for the first time, with a 25% statistical error on the 16 3 lattice and 15% on the 24 lattice. The complex amplitude A2 is calculated with small statistical errors. -
The Eightfold Way John C
The Eightfold Way John C. Baez, May 27 2003 It is natural to group the eight lightest mesons into 4 irreps of isospin SU(2) as follows: mesons I3 Y Q pions (complexified adjoint rep) π+ +1 0 +1 π0 0 0 0 π− -1 0 -1 kaons (defining rep) K+ +1/2 1 +1 K0 -1/2 1 0 antikaons (dual of defining rep) K0 +1/2 -1 0 K− -1/2 -1 -1 eta (trivial rep) η 0 0 0 (The dual of the defining rep of SU(2) is isomorphic to the defining rep, but it's always nice to think of antiparticles as living in the dual of the rep that the corresponding particles live in, so above I have said that the antikaons live in the dual of the defining rep.) In his theory called the Eightfold Way, Gell-Mann showed that these eight mesons could be thought of as a basis for the the complexified adjoint rep of SU(3) | that is, its rep on the 8- dimensional complex Hilbert space su(3) C = sl(3; C): ⊗ ∼ He took seriously the fact that 3 3 sl(3; C) C[3] = C (C )∗ ⊂ ∼ ⊗ 3 3 where C is the defining rep of SU(3) and (C )∗ is its dual. Thus, he postulated particles called quarks forming the standard basis of C3: 1 0 0 u = 0 0 1 ; d = 0 1 1 ; s = 0 0 1 ; @ 0 A @ 0 A @ 1 A 3 and antiquarks forming the dual basis of (C )∗: u = 1 0 0 ; d = 0 1 0 ; s = 0 0 1 : This let him think of the eight mesons as being built from quarks and antiquarks. -
Introduction to Elementary Particle Physics
Introduction to Elementary Particle Physics Néda Sadooghi Department of Physics Sharif University of Technology Tehran - Iran Elementary Particle Physics Lecture 9 and 10: Esfand 18 and 20, 1397 1397-98-II Leptons and quarks Lectrue 9 Leptons Lectrue 9 Remarks: I Lepton flavor number conservation: - Lepton flavor number of leptons Le; Lµ; Lτ = +1 - Lepton flavor number of antileptons Le; Lµ; Lτ = −1 Assumption: No neutrino mixing + + − + + Ex.: π ! µ + νµ; n ! p + e +ν ¯e; µ ! e + νe +ν ¯µ But, µ+ ! e+ + γ is forbidden I Two other quantum numbers for leptons - Weak hypercharge YW : It is 1 for all left-handed leptons - Weak isospin T3: ( ) ( ) e− − 1 ! 2 For each lepton generation, for example T3 = 1 νe + 2 I Type of interaction: - Charged leptons undergo both EM and weak interactions - Neutrinos interact only weakly Lectrue 9 Quarks Lectrue 9 Remarks I Hadrons are bound states of constituent (valence) quarks I Bare (current) quarks are not dressed. We denote the current quark mass by m0 I Dressed quarks are surrounded by a cloud of virtual quarks and gluons (Sea quarks) I This cloud explains the large constituent-quark mass M I For hadrons the constituent quark mass M = the binding energy required to make the hadrons spontaneously emit a meson containing the valence quark For light quarks (u,d,s): m0 ≪ M For heavy quarks (c,b,t): m0 ' M Lectrue 9 Remarks: I Type of interaction: - All quarks undergo EM and strong interactions I Mean lifetime (typical time of interaction): In general, - Particles which mainly decay through strong interactions have a mean lifetime of about 10−23 sec - Particles which mainly decay through electromagnetic interactions, signaled by the production of photons, have a mean lifetime in the range of 10−20 − 10−16 sec - Particles that decay through weak forces have a mean lifetime in the range of 10−10 − 10−8 sec Lectrue 9 Other quantum numbers (see Perkins Chapter 4) Flavor Baryon Spin Isospin Charm Strangeness Topness Bottomness El. -
ELEMENTARY PARTICLES in PHYSICS 1 Elementary Particles in Physics S
ELEMENTARY PARTICLES IN PHYSICS 1 Elementary Particles in Physics S. Gasiorowicz and P. Langacker Elementary-particle physics deals with the fundamental constituents of mat- ter and their interactions. In the past several decades an enormous amount of experimental information has been accumulated, and many patterns and sys- tematic features have been observed. Highly successful mathematical theories of the electromagnetic, weak, and strong interactions have been devised and tested. These theories, which are collectively known as the standard model, are almost certainly the correct description of Nature, to first approximation, down to a distance scale 1/1000th the size of the atomic nucleus. There are also spec- ulative but encouraging developments in the attempt to unify these interactions into a simple underlying framework, and even to incorporate quantum gravity in a parameter-free “theory of everything.” In this article we shall attempt to highlight the ways in which information has been organized, and to sketch the outlines of the standard model and its possible extensions. Classification of Particles The particles that have been identified in high-energy experiments fall into dis- tinct classes. There are the leptons (see Electron, Leptons, Neutrino, Muonium), 1 all of which have spin 2 . They may be charged or neutral. The charged lep- tons have electromagnetic as well as weak interactions; the neutral ones only interact weakly. There are three well-defined lepton pairs, the electron (e−) and − the electron neutrino (νe), the muon (µ ) and the muon neutrino (νµ), and the (much heavier) charged lepton, the tau (τ), and its tau neutrino (ντ ). These particles all have antiparticles, in accordance with the predictions of relativistic quantum mechanics (see CPT Theorem). -
Invariance Principles
Invariance Principles • Invariance of states under operations implies conservation laws – Invariance of energy under space translation → momentum conservation – Invariance of energy under space rotation → angular momentum conservation • Continuous Space-Time Transformations – Translations – Rotations – Extension of Poincare group to include fermionic anticommuting spinors (SUSY) • Discrete Transformations – Space Time Inversion (Parity=P) – Particle-Antiparticle Interchange (Charge Conjugation=C) – Time Reversal (T) – Combinations of these: CP, CPT • Continuous Transformations of Internal Symmetries – Isospin – SU(3)flavor – SU(3)color – Weak Isospin – These are all gauge symmetries Symmetries and Conservation Laws SU(2) SU(3) 8 generators; 2 can be diagonalized at the same time: rd I3 … 3 component of isospin Y … hypercharge SU(3) Raising and lowering operators Y = +1/2√3 Y = +1/√3 SU(3) SU(3) Adding 2 quarks SU(3) Adding 3 quarks Quantum Numbers • Electric Charge • Baryon Number • Lepton Number • Strangeness • Spin • Isospin • Parity • Charge Conjugation Electric Charge Quantum Numbers are quantised properties of particles that are subject to constraints. They are often related to symmetries Electric Charge Q is conserved in all interactions Strong ✔ Interaction Weak ✔ Interaction Baryon Number Baryon number is the net number of baryons or the net number of quarks ÷ 3 Baryons have B = +1 Quarks have B = +⅓ Antibaryons have B = -1 or Antiquarks have B = -⅓ Everything else has B = 0 Everything else has B = 0 Baryons = qqq = ⅓ + ⅓ + ⅓ -
Symmetry Disclaimer
SYMMETRY DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency Thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document. Report CTSLX, CALJFORI?IA INSTITUTE OF TKX”NLQGY Synchrotron Laboratory hsadena, California P “23 EIG.HTFOLD WAY: A TKEORY OF STRONG INTERACTION SYMMETRY* Ifwray Gell-Mann March 15, 196s (Preliminary version circulated Jan. 20, 1961) * Research supported in part by the U.S. Atomic Ehergy Commission and the Ufreci I?. Sloan Foundation. J CONTENTS Introduction P. 3 I1 The "bptons" as a Model for Unitary Symmetry P. 7 I11 Mathematical Descri-pkion of the Baryons pa 13 N Pseudoscalar Mesons po 17 V Vector Mesons p. 22 VI Weak Interactions p. 28 Properties of the New Mesons P. 30 VI11 Violations of Unitary Symmetry p. 35 3x Aclmarledgment s p. -
Kaon Reactions (Exp)
Kaon Reactions (exp) Rapporteur's talk: Chairman: Filthuth H. (Heidelberg) Rapporteur: Morrison D. R. 0. (CERN) Secretary: Yamdagni N. (Stockholm) Parallel sessions: SA. Total cross-sections, elastic scattering. Discussion leader: Lundby A. (CERN) Secretary: Blomqvist G. (Stockholm) SB. Inelastic two-body reactions. Discussion leader: Sens J. C. (FOM/CERN) Secretary: Jonsson L. (Lund) SC. Many-body reactions. Discussion leader: Goldschmidt-Clermont Y. (CERN) Secretary: Holmgren S. 0. (Stockholm) ' Review of Strong Interactions of Kaons D. R. 0. MORRISON CERN Introduction cross section is greater than the K+p cross section at all ener gies, including infinity. Naively it may be noted that in K-p This review of the strong interactions of K-mesons will be interactions the summed cross section for the channels divided into the following subjects K-+p-+ hyperon+pions (1) 1. Total cross sections 2. Elastic scattering is "'5 mb whereas such reactions do not exist in K+p interac 3. Inelastic two-body reactions tions presumably due to the absence of a positive strangeness 4. Many-body reactions 5. Production of "Rare" particles, p, 8, Q- 6. Summary and future. 26 o. Galbraith el al bl • IHEP-CERN (Preliminary) The outstanding results are: 25 1. The first data on total cross sections from Serpukhov 24 have given an unexpected result. 'j)' 23 2. A large amount of new data on elastic scattering has ..§., 22 become available, in particular polarisation experiments. The 0 '6 21 second peak is discussed. + t 3. In a two-body reaction a strong disagreement with Regge 20 + pole predictions has been ob. -
1. the SM of Particle Physics in a Nutshell the Electroweak And
1. The SM of Particle Physics in a Nutshell The electroweak and strong interactions of quarks and leptons are described by renormalizable quantum gauge theories. The principle of invariance of the theory under the transformation of a local gauge symmetry group fixes the dynamics. The particles that transmit the forces are thus called gauge bosons. They have spin 1 and have to be quantized according to Bose-Einstein spin statistics (bosons). The matter particles, the quarks and leptons, have spin and have to be quantized ¡ according to Fermi-Dirac spin statistics (fermions). Force acts on transmitted by electromagnetic all electrically charged particles photon (massless, spin 1) £ ¢ ¢¤£ ¥§¦ weak quarks, leptons, ¥§¦ (massive, spin 1) strong all colored particles 8 gluons (quarks and gluons) (massless, spin 1) PHY521 Elementary Particle Physics Symmetries are mathematically formulated using group theoretical methods: ¡ The transformations of local gauge symmetries are described by unitary § £ ¡ ¤¦¥ matrices, ¢ ( H: hermitian, quadratic matrix), with real, space-time dependent elements. The matrices ¢ form a group called U(n), SU(n) (det(U)=1). ¡ ¡ ¨ © U(n) has and SU(n) parameters, , and generators, , and can be £ written in terms of infinitesimal transformations as follows ( ): £ © ¢ U(n): £ © ¢ SU(n): Example: £ © ¢ Gauge group of the electromagnetic interaction: U(1) with ! . ! is the electric charge. Requiring the Dirac equation, which describes free electrons, to be invariant un- der these transformations leads to electron-photon interaction and the existence of massless photons. PHY521 Elementary Particle Physics Interaction symmetry group gauge theory electromagnetic unbroken local U(1): QED invariance under space-time dep. phase transitions generated by the electric charge strong unbroken local SU(3): QCD invariance under space-time dep. -
Properties of Quarks Isospin Many Groupings of Particles of Similar Mass and Properties Fitted in to Common Patterns
Properties of Quarks Isospin Many groupings of particles of similar mass and properties fitted in to common patterns. So far, we have discussed three families of leptons but isotopic spin or principally concentrated on one doublet of quarks , the One way to characterise these is using isospin , I. u and d. This quantity has nothing to do with the real spin of the particle, but obeys the same addition laws as the We will now introduce other types of quarks, along quantum mechanical rules for adding angular with the new quantum numbers which characterise momentum or spin. them. When the orientation of an isospin vector is considered, it is in some hypothetical space, not in terms of the x, y and z axes of normal co-ordinates. 1 2 Nucleons (p, n) , pi mesons ( π+, π0, π–) and the baryons known as ∆ (∆++ , ∆+, ∆0, ∆–) are three examples of groups of similar mass particles differing in charge by one unit. The rule for electric charge can then be written, The charge Q in each case can be considered as due to =( 1 + ) Q e2 B I 3 the orientation of an “isospin vector” in some where B is the baryon number which is 1 for nucleons hypothetical space, such that Q depends on the third and the ∆ and 0 for mesons such as the π. component I3. Thus the nucleons belong to an isospin doublet ≡ = 1 1 =1 − 1 In terms of quarks, the u and d form an isospin doublet, pI , I 3 2 , 2 n2 , 2 u= 1 , 1 =1 − 1 Similarly the pions form an isospin triplet , 2 2 d2 , 2 + 0 − 1 π = 1,1 π = 1, 0 π =1, − 1 (both with B = /3).